Several embodiments of a device for economically harvesting wave energy are disclosed. A sealed vessel for air storage, the spar buoy, is mostly submerged under water is also used as an inertial body that surface floats move relative to. The spar buoy may take many geometrical forms, but all have a stem that is above the water surface. Piston pumps are placed at the top of the stem. The pump has a gearing reduction to optimize the rotational motion of the pump drive shaft. Small angular motion at the drive shaft results in multiple cycles of linear reciprocal motion of the piston. Various mechanisms could convert the relative motion between the floats and the spar buoy to a rotational motion of the shaft. The compressed air generated by the pump is stored in the spar buoy and regenerated as electrical energy by expanding the compressed air in a turbine.